53O MATURATION AND IMPREGNATION OF THE OVUM. 



FIG. 2. Ripe ovum of Asterias glacialis enveloped in a mucilaginous envelope, and 

 containing an excentric germinal vesicle and germinal spot (copied from Fol). 



FIG. 3. Two successive stages in the gradual metamorphosis of the germinal vesicle 

 and spot of the ovum of Asterias glacialis immediately after it is laid (copied 

 from Fol). 



FIG. 4. Ovum of Asterias glacialis, shewing the clear spaces in the place of the 

 germinal vesicle. Fresh preparation (copied from Fol). 



more irregular in form and situated rather deeper in the vitellus. 

 By treatment with reagents the first clear space is found to be 

 formed of a spindle with two terminal suns on the lower side of 

 which is a somewhat irregular body (Fig. 5). The second clear 

 space by the same treatment is shewn to contain a round body. 



